1. Field of the Invention
The field of the present invention relates to semiconductor devices and manufacture methods, and more specifically, to limiting regrowth and threshold voltage (Vt) shift in such devices.
2. Background
Limiting regrowth and threshold voltage (Vt) shift has proven to be significant hurdle in gate first, metal gate, high k field effect transistor (FET) production, particularly where HfO2 gate dielectrics are used.
HfSiON may be used to reduce deleterious effects associated with regrowth and Vt shift. However, the scalability of conventional HfSiON based processing techniques, relative to HfO2-based processing techniques for example, is limited. For example, a thinner inversion thickness (Tinv) can be achieved using HfO2, but regrowth and Vt shift occurrence is more prevalent relative to HfSiON.